Wet and dry back head for rock drills



Patented July 31, l,1951

WET AND DRY BACK HEAD FOR ROCK DRILLS Earl B. Lear, Detroit, Mich.,assignor to Chicago Pneumatic Tool Company, New York, kN. Y., acorporation of New Jersey Application April 29, 1949, Serial No. 90,450`

This invention relates to operating controls for a rock drill, `and moreparticularly to a backhead having a novel arrangement of live air andwater supply passages.

The main object of this invention is the provi- Ysion of a rock drillhaving a backhead which is s o constructed and arranged that the toolmay ,beA operated .dryf i. e., with live air being supplied to the drillsteel during drilling operation, or wet, i. e., with waterr beingsupplied to the drin steel Whse drilling, and further that such Wetoperation may be controlled manually, er

automatically, as desired. By means of the invention it is possible toprovide four rdifferent backhead combinations for furnishing live air`or water to the drill steel for hole cleaningv purposes, withoutextensively dismantling the rock fdrill, andv with minimum loss of timein substituting parts.

Other objects and structural details of the invention will be moreapparent from the following description when read in conjunction withthe accompanying drawings wherein:

Fig. 1 is a longitudinal section view of the rear portion of a rockdrilljof the invention taken through lines I-I of Fig. 2, and showingthe backhead arranged for dry operation and with throttle in full-onposition;

Aline 4-4 ofFig. 3;

Fig. 5 is a section view of a rock drill of the invention showing thebackhead arranged for vwet operation with automatic 'control land withthe throttle in full-on position, and

Fig. 6 is a section View of the throttle valve as seen from line '--B ofFig. 2 and featuring the 4 claims. (c1. iai- 10) profile of va notchedflange as used on the throttle valve of the rock drill of the invention.

Vhaving a piston chamber I2 formed therein, and

a yhammer piston I3 reciprocable within the chamber to deliverpercussive blows to a working implement, such as a drill steel (notshown) fmounted at the front end of the drill.V The piston I3 isslidably mounted on a rifle bar I4 which is caused, by means including aratchet ring I5, to move in step-by-step rotary movement. Such movementis imparted to the piston I3 in the conventional manner by a nut I6 xedwithin the piston and engaging helical splines formed on the rifle bar.The reciprocating movement vof the piston I3 is eiected by live airadmitted to the tool under the control of an air throttle valve I'Ianddirected by a distributing Valve assembly, generally indicated at I8,to alternate ends of the chamber I2. The valve assembly I3 comprises ablock I9, a cap 2l, a chamber 22 formed therebetween, and a distributingvalve 23 positioned within the barrel II and encircling the shank of therifle bar I4,

Referring to Fig. 2 it will be seen that the throttle valve I'I ismounted transversely Within the backhead and comprises a central tubularportion 26, a notched flange 21 (Fig. 6) at the left thereof, `a portion28 of reduced diameter at the right of the valve, anda threaded portion2S at the extreme right thereof. For the accommodation of the valve I7,the backhead is formed with a central bore 3|, a bore 32 of reduceddiameter at the right thereof, and a counterbore 33 at the left thereof.The counterbore 33 is threaded in part for the reception vof thethreaded end portion 34 of `an air hose connection 35 (partly shown).The portion 28 of the throttle valve Il projects beyond the backhead andhas aiiixed thereto a manually operable lever 36 (partially shown inFig. 2) which is retained in position by nut 31. The throttle valve isrotatable to move a port 33, formed in the central tubular portion 25 ofthe throttle valve, into and out `of registry with an air passage 3Sformed in the backhead I0. When the throttle Il is moved from initial orinoperative position into itssuccessive operative positions (the iinaloperative position being shown in Fig. 1), live air flowing into athrottle chamber 4I within the throttle valve, is permitted to passthrough the port 38,

passage 39, reservoir 42, bore 43 of ratchet ring I5, a reservoir 44, aset of circumferentially arranged ports 45 Within the cap 2l, into thedis'- 'tributing valve chamber 22, and thence into alternate ends of themain piston chamber I2, to reciprocate the piston I3 in well knownmanner.

A bleeder port 38a, in the form of a groove, is arranged on theperiphery of the throttle valve and intersects a well of port 38, asseen in Figs. 1 and 6. The bleeder port 38a allows a reduced supply ofair to enter the drill for operation at slow speed or under reducedpower. I

The notched flange 21 (Fig. 6) cooperates with a plunger 41 (Fig. 2)which functions as a yielding locking means to retain the throttle valvein successive rotative positions to regulate the flow of live airsupplied for the operation of the rock drill. Plunger 41 is disposedwithin a bore 48 formed in the backhead, and is maintained against anotch 49 of the flange 21, when the throttle is in off position, by acompression spring I, arranged in the bore 48 and maintained undercompression by a threaded plug 52. As the throttle is rotated towardopen position, the plunger will successively engage the intermediatenotches 53, which are arranged to cause the throttle valve to supplylive air to the drill at reduced pressure by reason of bleeder port 38a.

If a full supply of air is desired the throttle is Y rotated to nalposition at which the plunger 41 engages notch 50. In this position ofthe throttle valve I1, the port 38 is .in registry with the passage 39,and the ilow of air from chamber 4I is unrestricted.

Dry operation For dry operation of the tool it will be seen in Figs. land 2, that a predetermined portion of live air owing into the reservoir42 passes rearwardly through port 54 into passageway 55, the lower endof which is closed by a threaded plug 56, into chamber 51, and throughapertures 58 in a plug 59 into a bore 6I of said plug, and thencethrough the longitudinal tube 62 and into the bore of the drill steel(not shown).

As is seen in Fig. 2, vprovision is made for the passage of water to thedrill steel by means of a threaded bore 63 located in the lower lefthand side of backhead I0, and a passageway 65 con- A necting bore 63 toa receiving chamber in the form of a bore 68 located toward the rightside of the backhead. A passageway 61 leads from L bore 68 into chamber51. A plug 69, having a reduced midportion 1I, is located in the bore68, the lower end being threaded to removably aiix the plug within thebackhead while the upper portion thereof seals a passageway 12 whichprojects upwardly from bore 68 and intersects the reduced diameter bore32, the uppermost end of passageway 12 being closed by a pipe .plug 13.When the tool is operated dry, a pipe plug 14 is applied to bore 53;however, as will be further explained, during wet operation of the tool,the flow circuit including passageway 65 as just described, conveyswater to the drill steel.

Wet operation The tool is arranged for two possible types of wetoperation, namely plain, wherein the flow of water 4is manuallycontrolled from a separate valve in the water delivery line, andautomatically, wherein the water control is coupled to and operates withthe air throttle valve, as will be fully described hereinafter.

Considering iirst the plain wet operation, reference lis had to Figs. 3and 4 wherein is shown the substitution of a plug 15 for the threadedplug 56. Plug 15 has an extension terminating in a head which fits thepassageway 55 to prevent the flow of air from reservoir 42 throughpassageway 55 into chamber 51. Pipe plug 14 is removed and a waterconnection 16 is threadably aixed to bore 63.

If the tool is being prepared for plain wet use exclusively, no otheralterations are required, the foregoing adjustments being suilicient to.place the tool in readiness for plain wet operation. If,

on the other hand, there is the possibility that it will be desired toconvert the tool to the automatic type, then the plug 69 is removed anda bushing 11 is tted in the bore 68. A plurality of radial holes 18connect the bore of bushing 11 to an annular lgroove 19 located on theexterior thereof, said groove 19 being in register with the passageway61 when the bushing is in place in bore 68. A plug 8|, similar to plug69 but having a stem of reduced diameter, extends within bushing 11, theupper end of the stem being adapted to seal the inner diameter of thebushing just above the radial holes 18, as shown.

It is seen that when the tool is arranged as in Fig. 3, water can ilowfrom the bore 63, through passageway 65 into bore 68, about the stem ofplug 8l through the bore of the bushing 11 and radial holes 18, intoannular groove 19, and iinally through ,passageway 61 to chamber 51 andinto the tube 62.

This latter plain wet arrangement can be quickly changed to theautomatic type by simply removing the plug 8l and inserting a smoothtting valve 82 into the bushing 11, as shown in Fig. 5. A valve head 83is arranged at the lower end of the valve and is acted upon by acompression spring 84, one end of which engages the valve, While theother end is enclosed in a recessed plug 85 which closes the lower endof bore 68. The valve head 83 is held against the lower end of bushing11 by the spring 84, thus preventing the flow of water through thebushing. The other end of valve 82 projects a short distance above theupper end of bushing 11 and is arranged for sliding contact with a cam86 'formed in the portion 28 of the throttle valve I1. When the throttlevalve I1 is rotated for tool operation, the cam 86 forces the valve 82downwardly thus unseating the lower end thereof and permitting water toflow to the drill steel; when the throttle valve is rotated for toolcut-01T, the valve 82 is urged by spring 84 to seating position,whereupon the ow of water to the drill steel ceases. I

In changing from dry operation to wet operation it is desirable,although notl essential, to replace the tube 62. The tube for use in wetoperation is preferably longer lthan the tube used for dry operation,and is further arranged to have a reduced diameter portion at the frontend thereof. The reason for arranging the wet operation tube in thismanner is, iirst, to permit the discharge of water at a point as closeas practical to the drill steel, and secondly, the reduced diameterportion provides for an increased rate of discharge velocity.

From the foregoing it is thus seen that the device of the invention iscapable of being arranged in any one of four possible combinations (seetable following) to provide for three distinct types of service, namely,dry, plain wet, and automatic Wet:

Operation Backhcad Arrangement Dry 1(15? plugsl74, g d

a uscp ugs 5, an water connection 76. Flam Wet {(b) use plugs. 75, 81,bushing 77, and water I connection 76. Automatic wet use plug 75, valve82, bushing 77, and water connection 76.

It should be apparent that, with the exception of the plain wetarrangement, the ilow of air or water through the tube 62 occurs onlyduring tool operation. As shown in Fig. 1 of the drawing, the toolincludes an air valve arrangement 88, which is used for blowing purposesat any time, whether or not the tool is in operation Such a blowingarrangement is similar to that shown and described in the U. S. patentto E. B. Lear, No. 2,177,391 dated October 24, 1939. Normally, the iiowof air through tube 62 supplies only enough air to keep the detritussuspended in the bore hole; the use of the blower arrangement 89 blowsthe detritus completely out of the bore hole. It will be understood thatthe air iiow .to the bore hole when using the blower valve, passes onthe outside of tube 62, in contrast to the flow of air or water withinthe tube 62 as when using the arrangement of subject invention.

What is claimed is:

1. A rock drill having a backhead arrangement which can be readilyadapted for any-one of a plurality of service requirements andcomprising a throttle valve for the control of compressed air to areservoir, a first passageway leading from the reservoir to a tube whichis arranged for the conduction of fluid to the work end of said rockdrill, a water inlet, a second passageway leading from said water inletto a bore which serves as a receiving chamber, a third passagewayconnecting said receiving chamber to said tube, a first set of removableplug means one of which closes the water inlet, another of which closesboth ends of the receiving chamber to condition the rock drill for dryoperation, and a second set of removable plug means for the replacementof said rst set comprising a plug for closing ythe first passageway, anda plug arrangement located in the receiving chamber to allow for iiow ofwater from the water inlet to the tube and having interchangeable partsyto provide for either manual control of the water iiow or automaticcontrol of the water ow by association with cam means on the throttlevalve, the second set of plug means being adapted to condition the rockdrill for wet operation.

2. A rock drill having a backhead arrangement adjustable for a pluralityof service requirements and comprising a throttle valve for the controlof pressure iiuid to a reservoir which is formed in part within thebackhead, a first passageway which leads from the reservoir to a tubepositioned within the rock drill, said tube adapted for the conductionof fluid to the work end of the rock drill, a water inlet in thebackhead, a second passageway which leads from the water inlet to theside of a bore forming a receiving chamber, a third passageway whichleads from the side of the receiving chamber to the tube, a first set ofremovable plug means to provide for dry operation of the rock drill andincluding a plug for closing the water inlet and a plug for closing bothends of the receiving chamber, and a second set of removable plug meansto provide for wet operation of ,the rock drill and including a plugyfor closing the first passageway and a plug arrangement adapted toallow for i'low of water from the second passageway, through thereceiving chamber, and into the .third passageway.

3. A rock drill having a backhead arrangement according to claim 2, inwhich the plug arrangement of the second set of removable plug meanscomprises a bushing positionable in part within the receiving chamberand two interchangeable water control plugs one of which closes bothends of the receiving chamber without restricting ow of water from thesecond passageway to Ythe third passageway, the other of which is in theform of a valve siidable within the `bushing and operable by cam meanslocated on the throttle valve :to control the flow of water from thereceiving chamber into the third passageway.

4. A rock drill having a backhead arrangement according .to claim 3, inwhich the valve is spring loaded to automatically shut off the iiow ofwater into the third passageway when the throttle valve is innon-operative position.

EARL B. LEAR.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,146,284 Sanders July 13, 19151,382,777 Gilman June 28, 1921 1,382,778 Gilman June 28, 1921 1,382,779Gilman June 28, 1921 1,531,315 Slater Mar. 31, 1925 1,804,066 Smith May5, 1931 1,941,205 Fuehrer Dec. 26, 1933

